Manufacturing method for laminated ceramic capacitor, and laminated ceramic capacitor

ABSTRACT

A method for manufacturing a laminated ceramic capacitor by firing a laminated body which includes dielectric ceramic layers containing a dielectric ceramic raw material powder and internal electrodes. The firing is carried out in accordance with a temperature profile in which the average rate of temperature rise is 40° C./second or more from room temperature to a maximum temperature. The dielectric ceramic raw material powder contains a BaTiO 3  system as its main constituent, and contains R (R is Sc, etc.), M (M is Mn, etc.), and Mg as accessory constituents, in which, when the total amount of the accessory constituents contained is denoted by D parts by mol with respect to 100 parts by mol of the main constituent, an the specific surface area of the main constituent is denoted by E m 2 /g, then D/E is 0.2 to 0.8.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of application Ser. No.13/403,019, filed Feb. 23, 2012, which is a continuation ofInternational application No. PCT/JP2010/062213, filed Jul. 21, 2010,which claims priority to Japanese Patent Application No. 2009-196346,filed Aug. 27, 2009, the entire contents of each of which areincorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to a method for manufacturing a laminated ceramiccapacitor and the laminated ceramic capacitor, and more particularly, animprovement in a method for manufacturing a laminated ceramic capacitor,and an improvement in the composition of a BaTiO₃ based dielectricceramic for use in a laminated ceramic capacitor which is suitable forthe improved manufacturing method.

BACKGROUND OF THE INVENTION

In laminated ceramic capacitors, for the purpose of reduction in size(reduction in thickness), it is effective to attempt to reduce inthickness not only of dielectric ceramic layers, but also of internalelectrodes. However, when the internal electrodes are further reduced inthickness, electrode disconnection is likely to be caused as a result ofa firing step for sintering of a raw laminated body. For example, thefollowing technique has been proposed as a technique which can preventthe electrode disconnection.

In Japanese Patent Laid-Open Publication No. 2008-226941 (PatentDocument 1), the rate of temperature rise adjusted to 500° C./hour to5000° C./hour in a firing step prevents electrode disconnection toachieve an electrode thickness of 0.8 to 1 μm.

In Japanese Patent Laid-Open Publication No. 2000-216042 (PatentDocument 2), structural defects such as cracks are prevented to increasethe reliability of a laminated ceramic capacitor obtained, in such a waythat the rate of temperature rise is adjusted to 500° C./hour or more at700° C. to 1100° C. in a temperature rising process for firing, theoxygen partial pressure in the atmosphere is adjusted to 10⁻⁸ atm orless at 1100° C. or more, and the oxygen partial pressure is adjusted to10⁻⁸ atm or more partially at 1100° C. or less in a temperature fallingprocess.

In Korean Patent Laid-Open Publication No. 10-2006-0135249 (PatentDocument 3), the temperature is increased at a rate of temperature riseof 10° C./second up to a temperature 20° C. lower than the maximumtemperature to achieve a balance between the prevention of electrodedisconnection and the prevention of overshoot during the temperaturerise (reaching a temperature higher than a desired firing temperatureduring the temperature rise).

While the prior art described in any of Patent Documents 1 to 3 achievesthe effect of allowing the internal electrodes to be reduced in layerthickness by means such as increasing the rate of temperature rise, theeffect has a limitation, and for example, in a laminated ceramiccapacitor including internal electrodes containing Ni as a conductivecomponent, it is extremely difficult to achieve 0.3 μm or less as anelectrode thickness after firing.

In addition, the atmosphere for firing a raw laminated body includinginternal electrodes using a base metal as a conductive component is, forexample, a N₂/H₂/H₂O system which needs to be controlled on a morereducing side than a Ni/NiO equilibrium oxygen partial pressure, andthis need will restrict the equipment and the material design.

In addition, when the ceramic contains, for example, a volatilecomponent such as Li, this volatile component is likely to scatterduring firing. Further, the residual volume of the volatile component islikely to vary depending on the size of the raw laminated body to befired, that is, the chip size, and the amount of charging a firingfurnace, and it is difficult to suppress the variation in this residualvolume.

On the other hand, laminated ceramic capacitors have been progressivelyreduced in size (reduced in thickness), and the dielectric ceramiclayers are becoming 0.5 μm or less in thickness. In order to respond tothis reduction in thickness of the dielectric ceramic layers, there is aneed for size reduction of the dielectric ceramic grains constitutingthe dielectric ceramic layers. Therefore, there is also a need formicroscopic grains of a dielectric ceramic raw material powder.

However, when the dielectric ceramic raw material powder is reduced insize, for example, to several nm level, grain growth is likely to bedeveloped during firing, and as a result, may lead to a problem that thelaminated ceramic capacitor is inferior in terms of lifetimecharacteristics under a high temperature load condition.

-   Patent Document 1: Japanese Patent Laid-Open Publication No.    2008-226941-   Patent Document 2: Japanese Patent Laid-Open Publication No.    2000-216042-   Patent Document 3: Korean Patent Laid-Open Publication No.    10-2006-0135249

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide a method formanufacturing a laminated ceramic capacitor, and the laminated ceramiccapacitor, which can solve the problems described above.

This invention is first directed to a method for manufacturing alaminated ceramic capacitor, which includes: a step of preparing a rawlaminated body including a plurality of stacked dielectric ceramiclayers containing a dielectric ceramic raw material powder, and internalelectrodes formed along the specific interfaces between the dielectricceramic layers; and a firing step of subjecting the raw laminated bodyto a heat treatment in order to carry out sintering of the raw laminatedbody, and characteristically has the following configuration in order tosolve the technical problems described above.

More specifically, in this invention, a temperature profile in which theaverage rate of temperature rise is 40° C./second or more from roomtemperature to a maximum temperature is adopted in the firing step.Further, in order for the composition and properties of the dielectricceramic raw material powder to be suitable for this high-ratetemperature rise, the following composition is adopted.

The dielectric ceramic raw material powder contains ABO₃ (A necessarilycontains Ba, and may further contain at least one of Ca and Sr; and Bnecessarily contains Ti, and may further contain at least one of Zr andHf) as its main constituent, and contains R (R is at least one selectedfrom Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, andLu), M (M is at least one selected from Mn, Cr, Co, and Fe), and Mg asaccessory constituents. Furthermore, when the total amount of theaccessory constituents contained is denoted by D parts by mol withrespect to 100 parts by mol of the main constituent, whereas thespecific surface area of the ceramic raw material powder for providingthe main constituent is denoted by E m²/g, D/E is 0.2 to 0.8.

In the method for manufacturing a laminated ceramic capacitor accordingto this invention, the firing step is preferably carried out inaccordance with a temperature profile in which the average rate oftemperature rise is 100° C./second or more from room temperature to themaximum temperature.

This invention is also directed to a laminated ceramic capacitorincluding: a laminated body configured by a plurality of dielectricceramic layers stacked, and a plurality of internal electrodes formedalong the specific interfaces between the dielectric ceramic layers; anda plurality of external electrodes formed in different positions fromeach other on the outer surface of the laminated body and electricallyconnected to specific one of the internal electrodes.

In the laminated ceramic capacitor according to this invention, adielectric ceramic constituting the dielectric ceramic layers containsABO₃ (A necessarily contains Ba, and may further contain at least one ofCa and Sr; and B necessarily contains Ti, and may further contain atleast one of Zr and Hf) as its main constituent, and contains R (R is atleast one selected from Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy,Ho, Er, Tm, Yb, and Lu), M (M is at least one selected from Mn, Cr, Co,and Fe), and Mg as accessory constituents, and the dielectric ceramicconstituting the dielectric ceramic layers has an average grain size of100 nm or less.

In the laminated ceramic capacitor according to this invention, thedielectric ceramic constituting the dielectric ceramic layers has anaverage grain size of 50 nm or less.

In the method for manufacturing a laminated ceramic capacitor accordingto this invention, the dielectric ceramic layers contain the accessoryelements which have the action of inhibiting the ceramic grain growth,and sintering is completed in a short period of time in the firing step.Thus, the segregation of the accessory elements is prevented from beingcaused as much as possible in the dielectric ceramic layers, and can bemade present homogeneously. Therefore, the grain growth during thefiring is made less likely to be developed, and the ceramic constitutingthe obtained dielectric ceramic layers can be composed of microscopicgrains.

Thus, in the laminated ceramic capacitor, even when the dielectricceramic layers are reduced in layer thickness, lifetime characteristicscan be made favorable in a high temperature loading test. In addition,the properties can be stabilized which are provided by the dielectricceramic layers. Furthermore, even when the additive amount of theaccessory elements is relatively small, the effect of the accessoryelements can be produced sufficiently.

In addition, according to this invention, in the internal electrodes,changes in state such as electrode disconnection and ball formation areprevented during the heat treatment in the firing step, and the internalelectrodes can be thus progressively reduced in layer thickness whilemaintaining the coverage of the internal electrodes at a high level,thereby making a contribution to the reduction in size of and theincrease in capacitance of the laminated ceramic capacitor.

In addition, the reduced layer thickness and increased coverage for theinternal electrodes are produced as a result of preventing the internalelectrodes from being shrunk, and voids, gaps, and the like at the endsof the internal electrodes can be thus also prevented from being causedat the same time. Therefore, the sealing property of the laminated bodyis improved after the heat treatment, and the reliability of environmentresistance can be also improved as a laminated ceramic electroniccomponent.

In addition, the shrinkage of the internal electrodes is prevented asdescribed above, and thus, in the case of extracting the internalelectrodes to a predetermined surface of the laminated body, the degreeof recess will be quite low at the extracted ends of the internalelectrodes. In addition, sintering is completed in a short period oftime in the firing step, and thus, almost no movement or segregation ofthe glass phase onto the surface will be caused due to the additivecomponent to the ceramic constituting the dielectric ceramic layers.Therefore, the step for exposing the extracted ends of the internalelectrodes can be skipped in the formation of external electrodeselectrically connected to the internal electrodes.

In addition, even when the dielectric ceramic constituting thedielectric ceramic layers contains volatile components (sintering aids)such as Li, B, and Pb, the volatile components is prevented from beingscattered by the heat treatment in the firing step, because sintering iscompleted in a short period of time in the firing step. As a result, theresidual volume of the volatile components can be prevented from varyingdepending on changes in the size of the laminated body and the amount ofcharging a firing furnace.

In addition, in the case of the laminated ceramic capacitor includinginternal electrodes containing, as a conductive component, a base metalsuch as Ni, there is conventionally a need in the heat treatment step toprecisely control the oxygen partial pressure in the atmosphere to nearthe equilibrium oxygen partial pressure of the base metal in order toachieve a balance between the prevention of the internal electrodes frombeing oxidized and the prevention of the ceramic from being reduced, andthis need complicates the design of a firing furnace. In contrast,according to this invention, the high rate of temperature rise in thefiring step can reduce the time for the heat treatment (ceramicsintering shrinkage), and thus, even in a more oxidizing atmosphere thanthe equilibrium oxygen partial pressure of the base metal, the heattreatment can be carried out almost without oxidation. Therefore, alaminated ceramic capacitor with high reliability can be manufacturedwhich has the dielectric ceramic less likely to be reduced and requiresno reoxidation treatment.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 is a cross-sectional view schematically illustrating a laminatedceramic capacitor produced by a manufacturing method according to anembodiment of this invention.

FIGS. 2(A) and 2(B) show mapping analysis images of an Mn element by awavelength-dispersive X-ray microanalyzer (WDX); wherein FIG. 2(A) issample 10 and FIG. 2(B) is sample 11 from Table 1, which were obtainedin order to assess dispersion states of accessory constituents indielectric ceramics constituting dielectric ceramic layers included in alaminated ceramic capacitor prepared in an experimental example.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1, the structure of a laminated ceramic capacitor1 will be described to which this invention is applied.

The laminated ceramic capacitor 1 includes a laminated body 2 as acomponent main body. The laminated body 2 includes a plurality ofdielectric ceramic layers 3 stacked, and a plurality of internalelectrodes 4 and 5 formed along the specific interfaces between thedielectric ceramic layers 3. One and the other end surfaces 6 and 7 ofthe laminated body 2 respectively have exposed ends of the plurality ofinternal electrodes 4 and 5, and external electrodes 8 and 9 are formedrespectively so as to electrically connect the respective ends of theinternal electrodes 4 to each other and the respective ends of theinternal electrodes 5 to each other.

For the manufacture of this laminated ceramic capacitor 1, the laminatedbody 2 in a raw state is first prepared by a well known method such asstacking ceramic green sheets with the internal electrodes 4 and 5printed thereon. Then, a firing step is carried out for sintering of theraw laminated body. Then, the external electrodes 8 and 9 are formedrespectively on the end surfaces 6 and 7 of the sintered laminated body2 to complete the laminated ceramic capacitor 1.

In this invention, a powder which has the following composition andproperties is used as a dielectric ceramic raw material powder, which isincluded in the ceramic green sheets to serve as the dielectric ceramiclayers 3 included in the laminated body 2 described above.

More specifically, the dielectric ceramic raw material powder containsABO₃ (A necessarily contains Ba, and may further contain at least one ofCa and Sr; and B necessarily contains Ti, and may further contain atleast one of Zr and Hf) as its main constituent, and contains R (R is atleast one selected from Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy,Ho, Er, Tm, Yb, and Lu) and M (M is at least one selected from Mn, Cr,Co, and Fe) as accessory constituents. Furthermore, in this dielectricceramic raw material powder, when the total amount of the accessoryconstituents contained is denoted by D parts by mol with respect to 100parts by mol of the main constituent, whereas the specific surface areaof the ceramic raw material powder for providing the main constituent isdenoted by E m²/g, D/E is 0.2 to 0.8.

In addition, in the firing step described above, a heat treatment stepof applying a temperature profile in which the average rate oftemperature rise is 40° C./second or more from room temperature to themaximum temperature is carried out according to this invention.Preferably, the temperature profile is adjusted to 100° C./second ormore.

The raw laminated body is preferably subjected to a degreasing treatmentbefore the heat treatment step.

In addition, after reaching the maximum temperature, cooling ispreferably carried out immediately without keeping the temperature inthe heat treatment step.

When the laminated ceramic capacitor 1 is manufactured by applying thehigh rate of temperature rise as described above while using thedielectric ceramic raw material powder, which has the composition andproperties as described previously, the dielectric ceramic constitutingthe dielectric ceramic layers 3 can have, as microscopic grains, anaverage grain size of 100 nm or less, preferably 50 nm or less.

It is to be noted that while the laminated ceramic capacitor 1 shown isa two-terminal type laminated ceramic capacitor including the twoexternal electrodes 8 and 9, this invention can be also applied tomulti-terminal type laminated ceramic electronic components.

An experimental example will be described below which was carried outfor confirming the effects of this invention.

(A) Preparation of Ceramic Powder for Main Constituent

First, a barium titanate powder and a barium calcium titanate powderwere prepared. Predetermined amounts of BaCO₃ powder and TiO₂ powder forthe barium titanate powder, and predetermined amounts of BaCO₃ powder,CaCO₃ powder, and TiO₂ powder for the barium calcium titanate powderwere each weighed, then mixed in a ball mill for 42 hours, and subjectedto a heat treatment for a solid-phase reaction to obtain a BaTiO₃(hereinafter, “BT”) powder and a (Ba_(0.90)Ca_(0.10))TiO₃ (hereinafter,“BCT”) powder.

In this case, each of the BT powder and the BCT powder was prepared soas to have target grain size and specific surface area (SSA) as shown inTable 1. It is to be noted that the grain size refers to an averagegrain size in the case of converting a SEM observation image to aspherical shape, whereas the SSA was measured by an apparatus(Multisorb) using a nitrogen adsorption method.

(B) Preparation of Dielectric Ceramic Raw Material Powder

In order to obtain samples 1 to 17 shown in Table 1, respective powdersof MgO, MnO, Dy₂O₃, and SiO₂ were blended as follows with each of the BTpowder and BCT powder obtained in the way described above.

Samples 1, 2, and 7 to 9: 100BT (or BCT)-1.0Dy-1.0Mg-0.3Mn-1.0Si

Samples 3 to 6: 100BT (or BCT)-10Dy-10Mg-3Mn-1.0Si

Samples 10 to 13, 16, and 17: 100BT (or BCT)-2.5Dy-2.5Mg-0.8Mn-1.0Si

Sample 14: 100BT-3.0Dy-1.1Mg-0.8Mn-1.1Si

Sample 15: 100BT-7.4Dy-2.7Mg-2.0Mn-1.1Si.

Next, these blended materials were mixed in a ball mill for 5 hours.Then, drying and dry grinding were carried out to obtain a dielectricceramic raw material powder.

(C) Production of Laminated Ceramic Capacitor

The dielectric ceramic raw material powder obtained with the addition ofa polyvinyl butyral based binder and ethanol was subjected to wet mixingin a ball mill for 5 hours to prepare a ceramic slurry.

Next, this ceramic slurry was formed by a die coater into the shape of asheet to obtain ceramic green sheets.

Next, a conductive paste containing Ni as its main constituent wasapplied by screen printing onto the ceramic green sheets, therebyforming conductive paste films to serve as internal electrodes.

In addition, as a measure for eliminating differences in level on theprincipal surfaces of the ceramic green sheets, which can be producedbetween the regions with the conductive paste films and the regionswithout the conductive paste films, a dielectric paste film of the samecomposition as the ceramic slurry was formed on the regions without theconductive paste films so as to have a thickness equivalent to that ofthe conductive paste film.

Next, the ceramic green sheets with the conductive paste films anddielectric paste films formed were stacked alternately so that the sideswere alternated to which the conductive paste films were extracted,thereby providing a raw laminated body including 5 effective layers.

Next, the raw laminated body was heated to a temperature of 300° C. inan N₂ atmosphere to burn the binder, and then the binder was burnedagain at a temperature of 700° C. in an N₂ atmosphere.

Then, in accordance with a conventional firing method, a heat treatmentof increasing the temperature at a rate of temperature rise in Table 1was carried out in a reducing atmosphere composed of a H₂—N₂—H₂O gaswith an oxygen partial pressure 10⁻¹⁰ MPa to obtain a sintered laminatedbody. In this case, the conditions of the maximum temperature in thefiring step and of the time for keeping at the maximum temperature wereset up as follows, depending on the rate of temperature rise.

The case of 50° C./min for Rate of Temperature Rise: keeping at amaximum temperature of 1200° C. for 5 minutes.

The case of 40 to 200° C./min for Rate of Temperature Rise: maximumtemperature of 1400° C. without keeping.

Next, a Cu paste containing a B₂O₃—Li₂O—SiO₂—BaO glass frit was appliedto both end surfaces of the sintered laminated body, and fired at atemperature of 800° C. in an N₂ atmosphere to form external electrodeselectrically connected to the internal electrodes, thereby providinglaminated ceramic capacitors as samples.

The laminated ceramic capacitors thus obtained had outside dimensions of0.5 mm in width and 1.0 mm in length, and the area of the electrodeopposed per dielectric ceramic layer was 0.3 mm². In addition, thedielectric ceramic layers were 0.3 μm in thickness, and the internalelectrodes were 0.3 μm in thickness.

(D) Evaluation

As shown in Table 1, evaluated were the grain size, the degree of graingrowth, and the number of defectives in a high temperature load lifetest.

The measurement of the grain size was made in such a way that thelaminated ceramic capacitors according to each sample were fractured andsubjected to thermal etching at a temperature of 1000° C., and thefractured surfaces were observed by using a scanning microscope. Morespecifically, the observation images were subjected to an image analysisto determine the equivalent circle diameters as the grain sizes. Theaverage value was calculated for the number of grains measured of 300,as the “Grain Size” shown in Table 1.

The degree of grain growth was calculated from the formula of “Degree ofGrain Growth”=“Average Grain Size after Firing”/“Grain Size of CeramicPowder for Main Constituent”.

In order to find the number of defects in a high temperature load lifetest, the high temperature load life test was carried out in which DC 4Vwas applied to the dielectric ceramic layers of 0.3 μm in thickness at atemperature of 85° C. to measure the change in insulation resistancewith time for the laminated ceramic capacitors according to each sample.In this case, 100 samples for each sample number were subjected to thehigh temperature load life test, and the sample was determined as adefective if the insulation resistance value was decreased to 100 kΩ orless before a lapse of 2000 hours.

TABLE 1 Number of Defectives Grain Size SSA of Main Total Amount in HighType of for Main Constituent of Accessory Rate of Grain The DegreeTemperature Sample Main Constituent Powder: E Constituent: D TemperatureSize of Grain Load Life Number Constituent Powder (nm) (m²/g) (parts bymol) D/E Rise (nm) Growth Test 1 BT 12 80 2.3 0.03  50° C./min 273 22.8100 2 BT 12 80 2.3 0.03 200° C./second 197 16.4 100 3 BT 12 80 23 0.29 50° C./min 260 21.7 100 4 BT 12 80 23 0.29 200° C./second 21 1.8 0 5BCT 14 72 23 0.32  50° C./min 245 17.5 100 6 BCT 14 72 23 0.32 200°C./second 22 1.6 0 7 BT 42 24 2.3 0.10  50° C./min 220 5.2 95 8 BT 40 252.3 0.09  50° C./min 247 6.2 100 9 BT 40 25 2.3 0.09 200° C./second 1533.8 50 10 BT 40 25 5.8 0.23  50° C./min 215 5.4 92 11 BT 40 25 5.8 0.23200° C./second 45 1.1 0 12 BCT 43 23 5.8 0.25  50° C./min 238 5.5 99 13BCT 43 23 5.8 0.25 200° C./second 49 1.1 0 14 BT 40 25 4.9 0.19 200°C./second 101 2.5 5 15 BT 40 25 12.1 0.49 200° C./second 43 1.1 0 16 BT40 25 5.8 0.23  40° C./second 55 1.4 0 17 BT 40 25 5.8 0.23 100°C./second 50 1.3 0

The following is determined from Table 1.

In the case of samples 1, 3, 5, 7, 8, 10, and 12 with 50° C./min for therate of temperature rise, the grain size is much greater than 200 nm dueto grain growth. Further, when the grain size is increased as describedabove, the number of defectives is also large in the high temperatureload life test.

On the other hand, among samples 2, 4, 6, 9, 11, and 13 to 17 with 40°C./second or more for the rate of temperature rise, the grain size isalso greater than 100 nm due to grain growth for samples 2, 9, and 14with D/E less than 0.2. Further, when the grain size is increased asdescribed above, the number of defectives is also large in the hightemperature load life test.

In contrast to these samples, in the case of samples 4, 6, 11, 13, and15 to 17 with 40° C./second or more for the rate of temperature rise andD/E of 0.2 to 0.8, the grain size is reduced to 100 nm or less, and thenumber of defectives is even 0 in the high temperature load life test.In particular, among these samples 4, 6, 11, 13, and 15 to 17, the grainsize is further reduced to 50 nm or less in the case of samples 4, 6,11, 13, 15, and 17 with 100° C./second or more for the rate oftemperature rise.

Furthermore, for example, when a comparison is made among samples 11,16, and 17, the samples are different only in rate of temperature rise:the rate of temperature rise of 200° C./second or more in the case ofsample 11; the rate of temperature rise of 40° C./second or more in thecase of sample 16; and the rate of temperature rise of 100° C./second ormore in the case of sample 17. As a result, the grain size is furtherreduced as 55 nm, 50 nm, and 45 nm, in the order of increasing the rateof temperature rise: samples 16, 17, and 11.

It is to be noted that although Table 1 shows no sample with D/E greaterthan 0.8, it has been confirmed that the D/E greater than 0.8 causes thesegregation of the accessory constituent to degrade the lifetimecharacteristics in the high temperature load life test, even if firingis carried out with high-rate temperature rise such as 40° C./second ormore, and further, 100° C./second for the rate of temperature rise inthe firing step.

FIGS. 2(A) and 2(B) show mapping analysis images of an Mn element by awavelength-dispersive X-ray microanalyzer (WDX), which were obtained inorder to assess dispersion states of accessory constituents indielectric ceramics constituting dielectric ceramic layers included in alaminated ceramic capacitor prepared in this experimental example. FIG.2(A) is an image for sample 10, and FIG. 2(B) is an image for sample 11.

It is to be noted that although FIGS. 2(A) and 2(B) are not intended toindicate the mapping analysis of the Mn element accurately because FIGS.2(A) and 2(B) are not presented in full color, it can be determined inthe black and white representation that the segregation of the Mnelement is caused more strongly when the contrast is greater.

Sample 10 and sample 11 are different from each other in the firingconditions of the rate of temperature rise, maximum temperature, andkeeping time. In the case of sample 11 with the high rate of temperaturerise of 200° C./second adopted, as shown in FIG. 2(B), there is lesssegregation of the Mn element as the accessory constituent, and the Mnelement is dispersed almost homogeneously. It is considered that thishomogeneous dispersion enhances the effect of inhibiting the graingrowth. In contrast, in the case of sample 10 with the low rate oftemperature rise of 50° C./second adopted, the segregation of the Mnelement is caused strongly as shown in FIG. 2(A).

It is to be noted that while Dy and Mn were used respectively as theaccessory constituent elements R and M in the dielectric ceramic rawmaterial powder in the experimental example, it has been confirmed thata similar effect is produced even in the case of using any of Sc, Y, La,Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu except for Dy asthe accessory constituent element R, or in the case of using any of Cr,Co, and Fe except for Mn as the accessory constituent element M.

DESCRIPTION OF REFERENCE SYMBOLS

-   -   1 laminated ceramic capacitor    -   2 laminated body    -   3 dielectric ceramic layer    -   4, 5 internal electrode

1. A laminated ceramic capacitor comprising: a laminated body configuredby a plurality of dielectric ceramic layers stacked, and a plurality ofinternal electrodes formed along specific interfaces between thedielectric ceramic layers; and a plurality of external electrodes formedin different positions from each other on an outer surface of thelaminated body and electrically connected to specific one of theinternal electrodes, wherein a dielectric ceramic constituting thedielectric ceramic layers contains ABO₃ as a main constituent thereof,and contains R, M, and Mg as accessory constituents thereof, and thedielectric ceramic constituting the dielectric ceramic layers has anaverage grain size of 100 nm or less, wherein A contains Ba, B containsTi, R is at least one element selected from Sc, Y, La, Ce, Pr, Nd, Pm,Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, and M is at least oneelement selected from Mn, Cr, Co, and Fe.
 2. The laminated ceramiccapacitor according to claim 1, wherein the average grain size is 50 nmor less.
 3. The laminated ceramic capacitor according to claim 1,wherein A further contains at least one of Ca and Sr.
 4. The laminatedceramic capacitor according to claim 3, wherein B further contains atleast one of Zr and Hf.
 5. The laminated ceramic capacitor according toclaim 1, wherein B further contains at least one of Zr and Hf.